Not all of the calls they get are timely: "It's the funniest thing," says one guard. "A person in the building will see the situation, but they won't call us for an hour, until they're pretty sure it's over."

Some guards are made so uncomfortable by the prospect of a couple making love in one of their buildings that they have taken measures to prevent it. "Now, when I see a guy and a girl stay in the building, I ask them to leave. I'm worried about liability--what if turns out that the woman is raped. That's a problem for Harvard, and it could be my job."

In fact, there is a growing climate of resentment among the guards. Why should they have to worry about horny students and professors?

"I've found people in laboratories, in classrooms," says one. "I've opened locked cleaning closets."

"There's been at least a dozen times when I've found a used condom on a classroom floor," he adds. "I don't worry about it. I just lock up. Thank God I don't clean the place."

Should he receive hazardous duty pay?

"At least a set of gloves, I'll tell you that."